This invention relates to large diameter saws such as those provided on tree cutting vehicles of the type which have tree felling and bunching heads which mount the saws in horizontal disposition in housings at the lower ends of the heads to cooperate with tree grasping and bunching arms provided above the housings for collecting and accumulating the severed tree stems. Vehicles of this general type are disclosed in U.S. Pat. Nos. 4,326,570 and 4,471,163, and U.S. Pat. No. 4,921,024 discloses a felling head for such a vehicle which incorporates a guard casing having a tree admitting opening which exposes the saw to a tree to be cut. The patents mentioned are incorporated herein by reference as are the following patents relating to circular saws generally, most to saws of the type used in saw mills.
______________________________________ 7,603 Knowles 1,811,079 Forsyth 2,559,355 Grupp 3,362,446 Potomak 3,866,504 Claesson et al 4,135,421 Bertram et al 4,326,570 Fridley et al 4,432,264 Scott 4,515,055 Scott 4,850,407 Inkster et al 4,921,024 Wiemeri et al ______________________________________
Typically, such vehicles today are used for cutting and thinning stands of trees and move along paths in a more or less continuous manner to sever the tree stems or trunks, while leaving the stumps in the ground. Trees up to, for instance, eighteen inches in diameter may be severed, and, if of small diameter, are carried along by the felling head until a bunch is accumulated. They, then, are deposited on the ground by the felling head in a bunch for later gathering by another vehicle. The smaller diameter saws suited to saw mill use are not generally suited to use on such felling heads where, typically, saws may be fifty inches in diameter and it is important to use a reduced number of more widely spaced cutting teeth which cleanly cut standing trees without imposing undue horsepower requirements on the saw drive motor. Normally, saw mill saws are, further, not particularly concerned with transporting the saw chips through some distance to a remote location for discharge, but this is a definite consideration for tree severing circular saws which operate in guard casings and take a considerable bite.